Printing telegraph receiver



1945- J. 'A. SPENCER ETAL PRINTING TELEGRAPH RECEIVER Filed April 30. .1943

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Jinan a1 Patented May 15, 1945 PRINTING TELEGRAPH RECEIVER James A. Spencer, Teaneck, N. J., and Leonhard F. Reinhold, Staten Island, N. Y., assignors to Radio Corporation of America, a corporation of Delaware Application April 30, 1943, Serial No. 485,186

21 Claims.

Our invention relates to improvements in printing telegraph receivers, and more particularly to printers of the class having a rotatable type wheel.

In carrying out our invention, we provide printing telegraph receiving apparatus which is intended to meet the following objects:

1. To provide a printing telegraph receiver having an improved design wherein the number of moving parts is minimized, as well as the need for servicing.

2. To provide a selecting mechanism especially adapted to function in response to the reception of uniform length code signals a common characteristic of which is that they have an invariable ratio between their marking and spacing code elements.

3. To provide code responsive means in combination with a plurality of selecting elements and-with a storage device whereby selected ones of said elements are caused to be simultaneously shifted, notwithstanding the progressive actuation or" said code responsive means.

4. To provide a receiving printer having a typewheel or other rotary member the setting of which is effected in accordance with the reception of different code signals, there :being an error indicating position which said typewheel automatically assumes upon failure of the associated selecting elements to be set up in accordance with any of the adopted code combinations.

5. To provide a printing telegraph mechanism in which the functional operation is so timed as to permit of re-setting the selecting elements substantially simultaneously with the printing operation in respect to a selected character.

6. To provide an error detector in association with a printing telegraph receiver having a rotary typewheel or the like.

7. To provide a printing telegraph instrument of the typewheel class having a plurality of internally notched code rings sufficient in number to be operably associated with an error detecting mechanism.

8. To provide means in a selecting mechanism for a printing telegraph instrument of the typewheel class whereby an exploring member mount? ed on the typewheel shaft is readily disengaged from the aligned notches in the selector rings so as to facilitate the restoration of said selector rings to normal. Such means preferably include a movable notched ring which is auxiliary to the selector rings.

Further objects of our invention are such as will appear to those skilled in the art from the detailed description of a preferred embodiment hereinafter set forth, and from the appended claims.

Our improved printer possesses certain novel features some of which may be .briefiy stated as follows:

Any suitable signal responsive means may be provided for individually selecting certain tripper members to be set in position for storing the permutation of a code signal. As illustrated such responsive means may comprise a plurality of magnets, one for each code element in a uniform length code signal. These magnets are used to actuate the trippers by which certain latch members are released. The latches are individually associated with detents, and the latter after being engaged by the latches, are caused to simultaneously trip selected ones of a set of selector rings. The selector rings are internally notched so that different permutational settings thereof will produce an alignment of notches at different points of their inner circumference. An exploring arm mounted on the typewheel shaft, when released and permitted to rotate within the selector rings, is arrested upon engagement with an alignment of notches. The printing operation is conventionally performed with the typewheel stopped in its selected position.

Substantially simultaneously with the printing operation, the selector rings are restored to their normal position. If, due to the reception of a mutilated signal, no character selection is made by the code selector rings, then the typewheel is permitted to rotate to a position just short of the home position, whereat an error symbol is caused to be printed. Each cyclic operation of the exploring arm is completed by bringing it to a stop at the home position, where it is arrested by an escapement pawl having two lugs. One of these lugs is used to stop the exploring arm at the error detecting position, but is normally moved out of the orbit of the exploring arm at the time of printing any selected character. The other lug acts to hold the exploring arm at the home position until a new setting of the code selector rings has been made.

Although the code' responsive magnets must of necessity be energized in the same progression as the selecting elements of the code signals, it is a feature of our invention that the code rings shall be moved to their selected positions simultaneously. This arrangement involves storage of the signal effects prior to the release of the code rings. The need for this mode of operation will be better appreciated when the requirements for wheel shaft.

anism are understood, and this matter will be hereinafter explained in full detail.

The driving means for our improved printer preferably include a continuously running motor, a worm shaft having two worms, friction clutches, each driven by a worm-wheel, one of the clutchesbeing mounted on the typewheel shaft and the other on a cam shaft, and operating lever mechanisms controlled in proper time sequence by followers which engage with the peripheries of two intermittently operative cams. An electromagnetic actuator is provided for the cam shaft clutch, and this is controlled by a series of two circuit closures, one of which is made in response to the reception of the first marking impulse in each code signal and the ing significance. The armatures 3 tend to rotate their appropriate triggers 2 counter-clockwise in opposition to the springs 4. The armatures 3 are pivoted as at 5. Each armature has an extension at the end of which is a button 6 bearing upon one arm or another of its associated trigger member 2.

There are seven trigger members 2 and whenever any one of them is actuated, it becomes locked in the actuated position by virtue of a shoulder portion 2a dropping under a lug 8a V which forms part of a latch member indicated other of which is timed in reference to the re- I ceiving distributor so as to follow each code signal.

As a background of art upon which applicants have built in devising the improvements herein disclosed, reference is made to Patent No. 2,183,147, granted December 12, 1939, to John B. Moore and Richard E. Mathes. That patent discloses the use of a seven-unit or an eight-unit code, the chief characteristic of which is that all code signals possess a uniform number of marking elements. Such a code lends itself to features of error detection which are provided for in the instant application.

Another patent which is herein referred to as prior art is No. 1,821,164, granted September 1, 1931, to Edward C. Kleinschmidt. The Kleinschmidt patent discloses the use of internally notched selector rings which are selectively operable to determine the stop position for a type- Applicants construction differs, however, in many respects from the apparatus shown and described by Kleinschmidt.

In the description to follow, reference is made to the accompanying drawings, wherein:

Fig. 1 is a front elevation of a preferred embodiment of our receiving printer selecting mechanism;

Fig. 2 is a plan view of the same mechanism shown in Fig. 1;

Fig. 3 is a fragmentary elevation view of certain control elements in the selector, these being shown as having been moved into a first stage of operation;

Fig. 4 is an elevation view of the selecting mechanism shown in Fig. 1, but with parts moved into a second stage of operation;

Fig. 5 is another fragmentary view showing parts moved into a third stage of operation;

Fig. 6 is still another elevation view showing parts moved into a fourth stage of operation; and

Fig. '7 is a diagram showing graphically the timing of the various operations of our improved printer.

Referring first to Figs. 1 and 2, the mechanism is controlled by seven code signal impulse responsive magnets l. Four of these magnets are arranged with vertical axes, while three others are arranged with horizontal axes in order that their armature extensions may individually engage with different tripper members 2, seven of the latter being pivoted on a common shaft.

Each of the magnets 1 corresponds to one of a series of seven code elements in a seven-unit generally at 8.. Each of seven latch members 8 is urged counter-clockwise by a leaf spring 9 and rotates onthe movable pivot pin III. In so doing, the hook portion 81) rises into engagement with a detent member II and particularly the downwardly projectinglug Ilb thereof.

The control of the tripper members 2 and the latch members 8 by the magnets l takes'place coincidently with the reception of the marking elements of the code signals. Upon reception of the first marking element, it is necessary to close certain contacts 12 in anticipation. of a second circuit closure which is timed to follow the reception of each code signal and which is used for magnetically actuating a clutch member hereinafter to be described. Control of the contacts I2 is obtained by actuationof a releasing bar 14 which underlies the left hand arms 8c of the latch members 8. This releasing bar 14 is integral with a lever arm Ma having a downwardly projecting catch thereon which engages with a detent forming part of a control lever Hi. The bottom end of lever 15 engages with a movable contact leaf spring I3 which supports one of the contacts 12. When levers Na and 15 are disengaged, the resilient bias in the spring 13 urges the two contacts I! into osculation.

A locally derived impulse from source 63 is timed by the multiplex receiving distributor contacts 64 to follow the reception of each complete code signal. This impulse becomes effective only if circuit closure is made through contacts I 2 and 64, so as to actuate a magnet l1 (Fig. 2) whose armature controls a friction clutch l8. This clutch is mounted on a cam shaft 19 which also carries a worm wheel 20 meshing with a worm 2| on a motor shaft 22. The armature of magnet l1 controls a tripping mechanism for the clutch 18 which is of the well-known single cycle type that permits the shaft 19 to make one revolution and then stops it at a homing position. The shaft l9 carries two cams 23 and 2| which engage respectively with cam follower rollers 25 and 26.

Cam follower 25 is mounted at the upper. extremity of a transfer lever 21. This lever is pivoted at 28 and at its lower extremity it carries a pivot pin I0 for all of the latch members 8. The transfer lever 21 also supports the springs 9 and the control latch M which cooperates with the contact control lever [5.

The mechanism thus far described is used to store and transfer the code element effects to a set of code rings 30. There are preferably seven of these rings corresponding to the code elements of a seven-unit signal. The rings are supported by posts 3| which carry comb plates 32 and spacers 33. The supporting means 3|, 32, and 33 hold the rings 30 loosely so that they are free to rotate on their axis. The rotative movement, however, is only very slight and is limited in one direction by the detents H and in the other direction by a stop member 34. The outer edges of the rings 39 are thus notched for engagement with the detent H and the stop member 34.

The selector rings 30 have code notches cut in their inner circumferential edges in a manner well known by those skilled in the art. That is to say, when the rings are selectively moved in accordance with the marking elements of a received code signal, there are different positions in which an alignment of notches will occur. A roller 35 is supported by a seeker member 36 which in turn is mounted on a rotatable exploring arm 3.1. The roller seeks and finds the selected alignment of notches in the rings 36. When the roller 35 moves radially into the aligned notches, the projection on the end of member 36 falls into a notch in a reset ring 38, the latter being mounted in a manner similar to that of the selector rings 38.

The member 36 is pivoted at 39 and its engaging projection is urged outwardly by a spring 85. The exploring arm 31 is mounted on the same shaft M which carries the typewheel (not shown). The shaft 4! is, however, driven by a friction clutch d2 in cooperation with which is a worm wheel 13 meshing with a worm 64 on the motor shaft 22. v

The motor t5 runs continuously. The exploring arm :37 is held at a homing position, however, against the urge of the friction clutch until released by the lifting of a start-stop lever it.

The start-stop lever 55 carries a, pin l! which engages with notches on the peripheries of the selector rings 39. Lever 45 also carries a detent it which engages with the extremity 37a of the exploring arm 31 and holds the latter stationary until the selected rings 39 are moved into their selecting positions. At that moment, the pin 47 on lever 38 rides out of the notches in the code rings and causes the detent 48 to be lifted out of the path of the exploring arm extremity 31a.

Returning now to the transfer lever 27 which is under control of the cam follower 25 and the cam 23, the follower 25 rides over a hump on the cam 23. Lever 21 then rocks clockwise on the pivot support 28. The detents H are thus pulled by the latch member 8 and movement takes place in the manner indicated by the changed positions of these elements in Figs. 3 and. 4 respectively. Only those of the detents H will be drawn to the left which have been selected by the magnetic control of the tripper members 2 and the disengagement of the corresponding latch members 8. As each of the detents Ii rotates on its pivot, its lug Ha disengages itself from a notch on the corresponding selector ring 35. Each selector ring is provided with a helical spring 55 whereby it is rotated clockwise through a small arc until arrested by the stop member 35.

At the same time that the selection transfer is made to the selector rings, it is necessary to restore the contacts I2 to an open circuit position. This is accomplished by engagement of the detents H with a pin 5! which is mounted on the contact control lever l5. The lever i5 is thus swung to the left and is eventually re-engaged by the releasing member l4 upon passing of the cam follower 25 off of the hump of cam 23.

As has been stated above, the exploring arm 31 when disengaged by the start-stop lever it is permitted to make an excursion from the homing position to a selected position determined by the alignment of notches in the code rings 30. At that point, the exploring arm, together with the type-wheel and shaft 4!, is arrested, and the typewheel is in position for printing a selected character. The printing operation takes place simultaneously with a restoring operation whereby the selecting mechanism is returned to its initial position. The restoration function is accomplished 'by a reset lever 52 which carries a cam follower roller 26 for engagement with the cam 26. Reset lever 52 is pivoted at 53 and carries a pin 55 at its right hand extremity for engagement in peripheral notches in the selector rings 30. When the lever arm 52 moves downwardly the pin 54 bears against the lower ends of the recesses in the rings 30 and moves those of the rings that have been selected back into their initial position where they are again locked in place by the detents II. This action takes place, however, before the printing operation has been completed. It is necessary, therefore, to hold the typewheel in place by other means. Such means comprise a pawl 55 mounted on a rocking member 56 which is pivoted at 51. The pivot support 5'! is fixed to the frame plate 68 (Fig. 2). The rocker arm 56 has an extension which underlies the reset lever 52. As the reset lever moves downwardly, it causes the rocker arm 56 by rotation to engage its pawl 55 with a selected space between teeth of a locking disk 58.

The reset ring 33, as well as the selector rings 50, are rotated counter-clockwise by the down- Ward movement of the reset lever 52. Reset ring 38 possesses no releasing detent II and, accordingly, it is allowed to rotate clockwise during the upstroke 0f the reset lever 52. The alignment of notches in the code rings 39 is upset by the restoring movement. The lug on the end of seeker member 36 is caused to ride out of a notch in the reset ring 38 because the roller 35 can no longer lie in the previously aligned notches. The exploring arm 31 remains stationary-only so long as the toothed disk 58 is locked in place by the pawl 55. When, however, the upward movement or" the reset lever 52 takes place, that is, after the cam follower 26 completes its traverse of.

the cam 24, then the typewheel shaft 41 is free. I

to rotate until the exploring arm 31 reaches its homing position and is thereat arrested by the dropping of the pin 41 into peripheral notches of the restored selector rings 30.

Provision is made in our improved receiving printer for the detection of errors whenever the received code signal is such that more or less than three of the selector rings 35 is actuated. Under such conditions, there will be no alignment of code ring notches, whereby the printing position of the typewheel may be selected. Were it not for the error detecting mechanism which is herein provided, the .exploring arm 31 would then continue'to rotate indefinitely until the code rings 30 were again restored to normal. The speed of rotation of the typewheel shaft is necessarily considerably greater than the rotational speed of the receiving distributor and of the cam shaft l9.

In order,,therefore, to overcome the objectionable features that would otherwise exist, as above mentioned, we preferably cause the exploring arm 3? to be arrested just short of its homing position whenever a mutilated signal is received or whenever mis-selection takes place due to any cause such as a mechanical defect of the selector mechanism itself. The arrest of the exploring arm 31 in a mis-selection position is produced b" engagement of its outer lug 310. with a lug 49 on the start-stop lever 46. The position of arrest of the exploring arm 31 in the case of a mis-selection is such that the typewheel will be locked in place for printing an error designating character. Upon restoration of the selector rings 38, the exploring arm 31 will take one step of. preferably about 3 to 5 into its homing position.

Our printer may be provided with conventional paper feed mechanism, printing platen, type-inking device, or ribbon, and caseshift mechanism for transferring the printing operation as between'letters and figures. tures are well known to those skilled in the art and are not involved in the disclosure of our improvements, it appears unnecessary either to show or to describe them.

The mode of operation.

In the operation of our improved printer,-it will be observed that the following steps are taken:

code rings 38 for clockwise movement. 4. Lifting of the start-stop lever 46, thereby to release the explorin arm 31. i

5. Rotation of the exploring arm 31 to a point where the roller 35 finds an alignment of code notches.

6. Arrest of the typewheel shaft H by engagement of the stop member 36 in one of the notches of the reset ring 38.

7. Downward movement of the reset lever 52, in the first portion of which counter-clockwise rotation of the code rings 38 and the reset ring 38 cause slight retrogression of the exploring arm 31 in order to disengage the stop member 38 from one of thev notches in the reset ring 38. Upon completion of the downward movement of the reset lever 52, pawl 55 is. engaged in a notch between teeth of the disk 58, thereby to lock the typewheel in selected printing position.

8. Operation of the printing platen-not shown because conventional.

9. Upward movement of the reset lever 52 which permits the reset ring 38 to be restored to its normal position, and also removes pawl 55 from engagement with disk 58, thereby to release the typewheel shaft Al for rotation of the exploring arm 31 to its homing position.

Operations which are concomitant with those above enumerated include the following:

At operation #2, which is illustrated in Fig. 3, it will be noted that the releasing bar M has been moved downwardly by the movement of the latch member 8 first to be tripped. Thev contact-controlling lever is thus released and is moved to the right by pressure of the contact spring l3. Contacts l2 are thereby closed.

In operation #4, as illustrated in Fig. 4, the retraction of the detents ll restores the lever I5 to its normal position in yvhich the contacts l2 are again caused to be opened.

The clutch-driven typewheel shaft rotates the exploring arm with sufficient speed so that it can make a complete revolution before the reset lever 52 moves downwardly. In case of a nus-selection, the exploring arm 81 will be stopped by the lug 49 on the start-stop lever 46, because this lever has not as yet been dropped back. into peripheral Since all of these fear ways.

notches on the code rings 30. It follows that the printing of an error designating character will take place under this condition.

During operation #5, the transfer lever 21 has a retrogressive movement in which the latch members 8 are disengaged from the detents II, and the lugs 8a are dropped back into the notches of the trigger members 2 to the left of the shoulders 2a. Members 8 and 2 are, therefore, restored to normal in readiness for the storage of subsequent signal elements. Also upon restoration of the latch members 8 to normal, the releasing bar l4 rocks clockwise and latches the contact spring controlling lever IS in normal position. All of these parts are then caused to occupy the positions shown in Fig. 5. The only difference between the showing of Fig. 5 and that of Fig. 1 is that in Fig. 5 the code rings 30 have not as yet been reset and the lugs Ila do not engage with steps on the code ring peripheries.

In order to understand more clearly how the steps of mechanical operation of the printer may be performed in respect of multiplex signals of one channel in a multiplex transmission, we have shown in Fig. 7 a timing chart in which a 360 scale represents one cycle of a three-channel distributor. This chart presumes the concurrent operation of three receiving printers at a terminal of the multiplex transmission system. During the passage of the distributor brush over different arcs of the code elements of successive character signals in different channels will be received.

Fig. '7 illustrates the printer operation for channel A only. The same timing chart for the other channels would, therefore, be displaced with respect to channel A by arcs of 120 and 240 respectively, taking the cycle of the distributor brush as a measure of time.

Operation of step #1, as above described, covers code reception which is clearly indicated by the block labelled channel A.

Block d represents the time required to perform the transfer operation whereby the code rings 30 are moved into their selected positions in accordance with the above described operation #3.

Block e represents the maximum travel time of the exploring arm 31. This travel time commences with the lifting of the start-stop lever 46, as mentioned in operation #4, and may end in any position within the block e, depending upon the particular character which is selected for printing.

Mis-selection results in printing an error designating character at the point reached by the exploring arm 37 when it is stopped by the lug 49 on the start-stop lever 46.

Block 7' represents the. time reserved for restoration of the code rings 30 and for actuation of the printing platen.

Beneath the blocks d and f are upwardly sloping lines representing the advancing strokes of the transfer lever 21 and the reset lever 52 respectively. The retrogressive strokes of these levers are represented by the downward slopes. The lines are labelled Code transfer stroke and Print and reset stroke respectively.

The features of our invention being such as above described, it. will be understood by those skilled in the art that we have provided improvements in a receiving telegraph printer such as to permit of operation in many advantageous The mechanism itself is relatively simple and requires'a minimum degree of maintenance 'may be employed.

servicing. Furthermore, many of the tried and proven features of printing telegraph receivers are retained.

It should be understood that we do not intend to limit ourselves in carrying out our invention to the use of the particular arrangement of code responsive magnets I for actuating the tripper members 2. Other means, well known in the art, For example as shown in the aforementioned Kleinschmidt Patent No. 1,821,164, the actuation of tripper members may be accomplished by a single code responsive magnet operating in conjunction with transfer mechanism whereby different tripper members may be actuated in succession so as to set up the particular code combination which represents a received signal.

Other means for actuating the tripper members 2 may consist of an arrangement of seeker pins controlled by a perforated code tape, where the seeker pins are arranged to transfer their movements respectively to individual ones of the tripper members 2 depending upon the tape perforations which are sensed. The use of tape controlled actuators for the tripper members 2 is not a part of the instant invention, but is simply mentioned as an alternative source of control in place of the selector magnets I which are herein shown and described.

Although our invention has been illustrated only by a single preferred embodiment, it will be observed by those skilled in the art that wide variations may be made in the details without departing from the spirit and scope of the invention.

We claim:

1. In a telegraph receiver, a typewheel shaft,

an exploring member mounted on said shaft, a plurality of internally code-notched selecting rings coaxially mounted with respect to said shaft, means for arcuately shifting said rings between non-selecting and selecting positions, and a shiftable internally notched stop-ring so constructed and arranged as to constitute means operable in advance of the restoration of the selecting rings to their non-selecting positions for disengaging said exploring member from an alignment of notches in said rings.

2. The combination according to claim 1 and including a toothed disk mounted on said shaft, and retaining pawl means engageable with said disk between its teeth, whereby said shaft and its typewheel are momentarily held in a selected printing position after disengagement of said exploring member.

3. In a telegraph receiver, a typewheel, a shaft therefor, an exploring member mounted on said shaft, means including at least seven internally code-notched selecting rings the notch faces of which. are adapted upon alignment to engage said exploring member at a code-selected point, thereby to arrest said typewheel in position to print a character, and other means for arresting said typewheel in an error designating position upon failure of the first said means to cause an intended arrest, said other means including a detent cooperating with a stop-arm which rotates with said shaft, the detent being interposed in the path of said stop-arm in response to a misselection of said,selecting rings.

4. The combination according to claim 3 wherein said selecting rings are so constituted and arranged that an invariable number thereof is required to be shifted to a selecting position in gaging the clutch last mentioned at a predeter-' response to a code signal in order to engage said "exploring member.

5. A printing telegraph instrument comprising a plurality of internally code-notched selector rings, detent members arranged to individually restrain the movement of said rings under resilient compulsion until a predetermined phase of a printing cycle is reached, marking-code-signalresponsive storage means for selecting a character designating combination of said rings to be released by their detent members, a typewheel mounted for rotation on a shaft, an exploring arm also mounted on said shaft and arranged to seek an alignment of code notches in said rings upon permutational setting of the same, means for rotating said typewheel into position to print a selected character, means for resetting said selector rings to their initial position, and means for holding said typewheel in printing position until after the resetting of said rings. I

6. An instrument according to claim 5 and including a catch-and-release pawl operableat times to arrest said exploring arm in a homing position, and at times to arrest the same so that an error symbol may be printed by the typewheel.

7. An instrument according to claim 5 and in cluding a movable index ring wherewith'saicl exploring arm is engaged while resetting said selector rings.

8. In a printing telegraph instrument, a plurality of code signal responsive units arranged to be progressively actuated, a plurality of internally notched rings concentrically disposed with respect to a typewheel shaft, a typewheel and an exploring arm mounted on said shaft, motordriven transmission gearing, including friction clutches for cyclically actuatingthe mechanism of said instrument, a signal storage unit including a detent individually associated with each said ring, for simultaneously releasing selected rings, means for causing selected ones of said signal responsive units to progressively condition their appropriate detents for release of corresponding rings, and mechanism'dr'iven through one of said clutches for timing said release in relation to the rate of reception of the character code signals.

9. 'The combination according to claim 8 and including electromagnetic tripping means for enmined instant following the reception of a given character code signal.

10. In a printing telegraph, a typewheel, an index arm rotatable with said typewheel, a plurality of internally notched selector rings selectively operable in accordance with code combinations of impulses for determining a stop position for said index arm, whereby said typewheel is arrested in a printing position, a movable index ring engageable with said index arm for backing the same out of said stop position, means operable after performance of a selective function by said selector rings for restoring the same to a normal position, and means for applying the disengaging movement to said index ring in advance of the selector ring restoration.

11. In a signal translator, a character designating member mounted on a rotatable shaft, an index arm fixed to said shaft, a plurality of at leastseven internally notched selector rings, means operable in accordance with code combinations of impulses for conditioning said selector rings to arrest said index arm, and, with it, said character designating member, means for disengagingsaid' index arm from a selective alignment of notches in said rings, thereby to cause its rotation to be resumed, stop means engageable with said index arm in'a homing position, and short-stop means engageable with said index arm upon failure of said selector rings to arrest said index arm during an operating cycle, whereby said character designating member is arrested in an error designating position.

12. In a printing telegraph, a typewheel, means for rotating said typewheel from a homing position to a character printing position or teen error designating position, a plurality of at least seven internally notched code rings selectively operable in accordance with received code combinations of impulses for arresting said typewheel in a selected character printing position, and means for causing the arrest of said typewheel in said error designating position whenever more or less than a predetermined number of said code rings is selectively operated, the last said means comprising a stop-arm rotatable with said typewheel, and a detent having two lugs arranged to intercept said stop-arm, one of said lugs being effective to arrest said typewheel in a homing position and the other lug to arrest the same in said error designating position.

13. In a printer, a rotatable typewheel, at least seven selectors, means for setting said selectors in accordance with the marking units of a received character code signal, a stop device rotatable with said typewheel and engageable by said selectors to stop the typewheel in a selected printing position whenever said selectors respond to a true character code signal, a detent normally operable to stop said typewheel at a homing position at the end of each operating cycle, and means for so positioning said detent that it stops the typewheel short of the homing position upon failore of said selectors to engage said stop device during an operating cycle.

14. The combination according to claim 13 and including means for causing said typewheel to print an error symbol whenever it is stopped by the positioning of said detent under control of the last said means.

15. In a telegraph printer, a rotatable typewheel, means including a plurality of disk selectors and an exploring arm engageable therewith for causing said typewheel to be arrested in a selected character printing or blank posi-' tion, detent means operable by any one of said selectors to initiate a cyclic movement of said exploring arm in fixed phase relation to the typewheel, said detent means having two lugs, one for initiating said cyclic movement, and the other lug for at times intercepting said exploring arm short of arrival at its home position, code-signal responsive means for permutationally actuating said disk selectors, and means operable subse quent to each truly selective operation of the first said means whereby said other lug is prevented from intercepting said exploring arm.

16. In a telegraph receiver, a plurality of at least seven internally notched selector rings, a rotatable shaft,means operable to hold said shaft in a homing position until released for friction drive, a stop arm fixedly mounted on said shaft, means pivoted on said stop arm and urged centrifugally against the inner circumferential edges of said rings for seeking an alignment of notches therein, means responsive to true code signals for.

so setting a fixed number of said 'ringsthat the position of notch alignment is different for each character selection, means for registering the effects of each true character selection as denoted by the point at which said stop arm is arrested, and means for causing the arrest or said stop arm in an error designating position which is just short of said homing position upon failure of said responsive means to efi'ect a true setting of the selector rings. a

1'7. Selecting mechanism responsive to the reception of different permutations of equal length code signals, comprising a plurality of selector disks, resilient means for actuating each said disk, a detent normally engaged with a peripheral step on each said disk for restraining the movement thereof, a plurality of latch members each individually associated with a respective one of said detents and each corresponding to a different one of the code elements in said signals, means responsive to signal pulses for successively actuating selected ones of said latch members, a first circuit-closing device operable by that one of said latch members which is first actuated during reception of a code signal, a second circuit-closing device in series with the first and operable in fixed sequence to the code signal reception, means including a rotatable cam and a lever-supported cam follower for causing the simultaneous release of those selector disks which are engaged by selected ones of said detents, electromagnetic clutch-controlling means operable by said sec-- ond circuit-closing device for initiating a cycle of rotation of said cam, means for utilizing the effects of permutational selection of said disks, a second cam having a shaft common to the aforesaid cam, a second cam follower cooperating with said second cam, and means operable by said second cam follower for restoring said disks to their initial positions.

18. The combination according to claim 17 and including error detecting mechanism operable by the selection and release of an abnormal number of said selector disks.

19. Mechanism for selectively orienting a rotatable shaft and for arresting the same in a predetermined position, comprising clutch-andrelease means for normally holding said shaft in a homing position,-a plurality of internally codenotched selecting rings, an exploring member mounted on said shaft and having stop means thereon arranged to seek and to enter a transverse alignment of code notches in said rings as 7 brought about by permutational setting of the rings, the normal ratio being constant between the number of rings responding to a setting movement and the number of rings retained in normal position, and other means for arresting said shaft short of said homing position whenever an erroneous ratio exists between the number of said rings set and the number not set.

20. Orientation setting mechanism for a rotatable shaft comprising a plurality of internally notched selector rings, detent members arranged to individually restrain the movement of said rings under resilient compulsion until a predetermined phase of an operating cycle is reached, marking-code-signal-responsive storage means for selecting a permutational combination of said rings to be released by their detent members, an exploring arm mounted on said shaft and arranged to seek an alignment of code notches in said rings upon permutationally-setting the same, means for rotating said shaft into the selected position, means for resetting said rings to their initial position, and means for holding said shaft in its selected position of orientation until after the re-setting of said rings.

21. In a translator of permutational code signals which are characterized by the existence of a fixed ratio between the number of marking elements of equal length and the number of spacing elements of equal length, a plurality of code responsive selector mechanisms each individual to a different code element, a rotatable shaft, internally notched selector rings disposed coaxially with respect to said shaft, each ring being operatively associated with a respective one of said selector mechanisms, a stop device fixed to said shaft and carrying a seeker capable of exploring JAMES A. SPENCER. LEONHARD F. REINHOLD. 

